This invention relates to spectrometers, and more particularly, to small profile spectrometers.
A spectrometer is an instrument for measuring the wavelengths of electromagnetic radiation. Typical laboratory spectrometers are bench size instruments and include a sample holder, a light source, an optical prism, and an electronics package. In operation, the light source illuminates a sample held by the sample holder, the optical prism separates light passing through the sample into wavelength bands, and the electronics package measures the intensity of the light in each of the wavelength bands. Spectrometers are often included in analytical instruments that identify the wavelengths of light absorbed by liquids, solids, and gases. Identifying absorbed wavelengths permits the identification of chemicals included in the liquids, solids, or gases being analyzed.
One application of laboratory spectrometers is the analysis of lubricants used in industrial machinery, such as earth moving equipment, aircraft, such as commercial jetliners, and long-haul trucks. By analyzing a lubricant, and identifying an optimum time for changing a lubricant in industrial machinery, aircraft, or long-haul trucks, the costs of operating such equipment can be reduced.
Lubricants are liquids or solids that reduce friction and wear of machine components, such as gears, in industrial, automotive, and transportation equipment. A machine component that requires lubrication will continue to perform satisfactorily as long as the lubricating oil or grease protecting it is kept clean and free from contaminants and abrasive particles, and the machine component itself does not deteriorate from wear. Lubricants can oxidatively break down, leading to the formation of degradation products. If oxidation becomes severe, the lubricant will corrode the critical surfaces of a component.
Monitoring lubricant quality during the course of machine operation is thus necessary to ensure optimal machine performance. Changes in lubricant properties such as viscosity or color may indicate that a lubricant has exceeded its useful life and must be changed. Changes in other properties, such as increases in the concentration of particulate matter, or changes in the level of chemical contaminants, may provide additional information about the wear of machine components. Lubricant monitoring typically requires interruption of machine operation to permit lubricant sampling. Samples are analyzed, typically offsite, by xe2x80x9cwet benchxe2x80x9d chemical techniques. These techniques can be costly and time-consuming. In addition, they are not performed in real time.
Infrared spectroscopy analysis using a laboratory spectrometer represents an alternative to xe2x80x9cwet benchxe2x80x9d methods. Fourier transform infrared spectroscopy, coupled with multivariate data analysis techniques, enhances the utility and sensitivity of infrared spectroscopy as a tool for lubricant quality analysis. The information contained in the infrared spectrum of a lubricant includes information at the molecular level about the chemical composition of the lubricant, the additives present, and the degradation products that were generated as a result of breakdown of the lubricant. Fourier transform infrared spectroscopy of lubricants can indicate whether and to what extent the lubricants have undergone oxidative degradation, as well as contamination due to free water, antifreeze, nitrogen fixation, soot deposits, and fuel dilution.
Unfortunately, infrared spectroscopy using laboratory spectrometers has several disadvantages. First, laboratory spectrometers are expensive. It is not uncommon to for a laboratory spectrometer to cost more than $15,000. Second, laboratory spectrometers are bulky and often occupy a space equivalent to the space taken up by a large desk. Third, a trained technician is often required to operate a laboratory spectrometer, which increases the cost of analyzing a sample. Fourth, samples for analysis must be brought to the laboratory spectrometer site for analysis.
For these and other reasons there is a need for the present invention.
The present invention provides a small profile spectrometer that can be used, in one embodiment, to monitor lubricant quality in machines. The spectrometer measures the absorption of electromagnetic energy in a lubricant at a specified frequency (or frequencies) characteristic of lubricants, lubricant breakdown products, or other contaminants.
In one embodiment a spectrometer is provided that includes one or more electromagnetic energy emitters, one or more electromagnetic energy detectors, and an optical path including a sampling element. The optical path optically couples each of the one or more electromagnetic energy emitters to one of the one or more electromagnetic energy detectors.
In an another embodiment, a method is provided that includes generating one or more infrared radiation beams, each of the one or more infrared radiation beams having an intensity, transmitting each of the one or more infrared radiation beams along an optical path that includes a sampling element optically coupled to a sample material to produce one or more attenuated infrared radiation beams, measuring the intensity of each of the one or more attenuated infrared radiation beams to produce one or more intensity measurements, and processing the one or more intensity measurements to identify one or more properties of the sample material.